It's hard to avoid stupid people nowadays. They're EVERYWHERE.
Recently I stumbled upon a blog. Everything seems normal, but then the guy decides to give out his phone number?! That may be okay if it was some sort of business, however, it was a blog. Kind of useless. In fact, within a few minutes I can pin point exactly where he lives. His address, etc. I could get a satellite view of his house, and obtain information about his history. Kind of scary isn't it?
I know there are more examples, but that's all I can think of.
So, post away. I know you've seen someone do something on the internet that makes you want to hit your head on the wall.